Download The Parasympathetic Ganglia in the Head and Neck

Lecture: 11
Anatomy and Physiology of
Parasympathetic Nervous System
Dr. Eyad M. Hussein
Ph.D of Neurology
Consultant in Neurology Department,
Nasser Hospital,
Assistant Professor,
Faculty of Medicine, Islamic University
Faculty of Dentistry, University of Palestine
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‫الشكر‬
Anatomy of the Autonomic Nervous System
(Involuntary Nervous System or Visceral Nervous System)
Definition: it is the involuntary nervous system which
supplies:
•
Unstriated (smooth) muscles of the viscera and
blood vessels.
•
Cardiac muscles.
•
Glands.
Structures of the Autonomic Nervous System
1. Sympathetic nervous system (Thoraco-lumbar).
2. Parasympathetic nervous system (Cranio-sacral).
Parts of the Autonomic Nervous System
1. Central part: consists of autonomic nuclei in the
brain stem, thalamus, hypothalamus and insula.
2. Peripheral part: consists of:
•Sympathetic nervous system (SNS).
•Parasympathetic nervous system (PSNS).
The Origin of the Autonomic Nervous System
The origin of the sympathetic nervous system:
Consists of fibers which arise from the 12 thoracic and upper
2 lumbar segments (Thoraco-lumbar part) and reach the
sympathetic chain by the white rami.
2. The Origin of the Parasympathetic Nervous System:
a. The cranial part: consists of fibers which pass in
four cranial nerves (3, 7, 9 & 10 cranial nerves)=10973
b. The sacral part: consists of fibers which arise
from the S2, S3, and S4 segments of the spinal cord.
The Peripheral Autonomic Nervous System
• Most of the visceral structures are supplied by two
systems (receive sympathetic and parasympathetic nerves).
• The SNS supplies:
1. Skin of the body (its arterioles, sweat glands).
2. Blood vessels of the limbs (its smooth muscles).
3. Deep viscera.
• The PSNS supplies the deep viscera only.
• Each of the two systems consists of two order neurons.
1. First Order Neurone
• It is formed by:
1. The nerve cells of certain nuclei in the brain stem.
2. Lateral horn cells (intermediolateral nuclei) of the
spinal cord: D1-L2 and and AHCs of S2-S4.
•
The axons of these cells carry stimuli to the autonomic
ganglia (called preganglionic fibers which are
myelinated).
2. Second Order Neurone
• It is formed by the nerve cells in the sympathetic
and parasympathetic ganglia.
• The axons of these cells carry stimuli to the
viscera (called postganglionic fibers which are
non-myelinated)
Types of Autonomic Ganglia
They are present outside the CNS and may be:
1. Paravertebral ganglion (Sympathetic): as
sympathetic trunk (chain).
2. Collateral ganglia (Peripheral or Sympathetic): as
celiac, superior mesenteric and inferior mesenteric
ganglia.
3. Terminal ganglia (Parasympathetic): they are present
on the walls of the viscera.
Notice that:
1.
The sympathetic preganglionic fibers are short, while
the postganglionic fibers are long.
2.
The parasympathetic preganglionic fibers are long.
3. while the postganglionic fibers are short.
4.
The preganglionic fibers are myelinated.
5.
The postganglionic fibers are non-myelinated.
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Transmitters of the Autonomic Nervous System
1. The preganglionic transmitter:
For sympathetic and parasympathetic preganglionic
transmitter is Acetylcholine.
2. The postganglionic transmitter:
a. All postganglionic fibers of the parasympathetic are
Acetylcholine.
b. The majority of sympathetic postganglionic fibers are
Epinephrine and Norepinephrine. The few which
are known to be Acetylcholine (for the sweat glands and
some cutaneous and skeletal muscle blood vessels).
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How are the Visceral Structures Supplied
by Autonomic (Motor) Fibers?
The autonomic supply to the visceral structures in two points:
1. Most of the visceral structures have two nerve supply: one
sympathetic and one parasympathetic. One of these nerves
acts "stimulator" while the other acts "inhibitor".
2. Each of two motor nerves (sympathetic and
parasympathetic) is formed of a chain of two neurons:
a. The body of the first neuron is found in the CNS
and its axon is called a preganglionic fiber.
b. The body of the second neuron is found in the
PNS and its axon is called a postganglionic
fiber.
The Parasympathetic Nervous System
Cranio-Sacral System
The parasympathetic NS consists of two parts:
1. The cranial part: in nuclei of 3, 7, 9 & 10
cranial nerves in brain stem) = 10973.
2. The sacral part: it formd by the cells of
intermediolateral nucleus in the anterior horns of
S2, 3, 4 segments of the spinal cord.
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A. The Cranial Part of the PSNS
1. Oculomotor Nerve (III)
 First order neuron: Edinger-Westphal nucleus in midbrain.
Second order neuron: Ciliary ganglion.
 Preganglionic fibers: the axons of the Edinger-Westphal
nucleus pass in the oculomotor nerve (nerve to inferior
oblique muscle) and relay in ciliary ganglion.
 Postganglionic fibers: the axons of the ciliary ganglion
give short ciliary nerves which supply the sphincter
pupillae and ciliary muscles.
2. Facial Nerve (VII)
First order neuron: superior salivary nucleus in the pons.
 Fibers: the axons of these cells pass in the facial nerve then
run in two branches of facial nerve:
1. Preganglionic fibers (Greater petrosal nerve): which
relays in pterygopalatine ganglion (second order
neuron).
• Postganglionic fibers: from this ganglion to the
lacrimal gland, and glands of the nose , palate and
pharynx.
2. Preganglionic fibers (Chorda tymbani ): which relays in
sbmandibular ganglion (second order neuron).
• Postganglionic fibers: arise from the ganglion to
supply the submandibular and sublingual salivary
glands.
3. Glossopharyngeal Nerve (IX)
 First order neuron: Inferior salivary nucleus in the
medulla oblongata.
 Second order neuron: Otic ganglion.
 Preganglionic fibers: the axons of the inferior salivary
pass in the lesser petrosal nerve and relay in otic
ganglion.
 Postganglionic fibers: the axons of the otic ganglion
join with the auriculotemporal nerve to supply the
parotid gland.
4. Vagus Nerve (X)
 First order neuron: dorsal nucleus of vagus in the medulla
oblongata.
 Preganglionic fibers: are formed by the axons of these cells
which pass in the vagus nerve (relay in many ganglion in
different organs in the thorax and abdomen).
 Postganglionic fibers: the axons of the terminal ganglia in
the different thoracic and abdominal organs pass directly to
supply:
• Heart, bronchi, lung, liver, pancreas, kidneys, esophagus,
stomach, small intestine, and large intestine (up two
junction of right 2/3 and left 1/3 of transverse colon), liver,
pancreas, kidneys.
B. The Sacral Part of the PSNS
 First order Neuron: are formed by the cells of the
intermediolateral nucleus of the anterior horn of the
S2, S3 & S4 segments of the spinal cord.
 Preganglionic fibers: are formed by the axons of the
cells in the lateral horn of S2, S3 & S4 segments of the
spinal cord → ventral rami of S2, S3 & S4 spinal nerves
→ pelvic splanchnic (nervus erigens), which pass
directly to synapse with the terminal ganglia present on
or in walls of the pelvic viscera.
 Postganglionic fibers: arise from the cells of these terminal
ganglia to supply:
1. Left 1/3 of the transverse colon, descending colon, pelvic
colon, and rectum.
2. Urinary bladder:
•The muscles of its wall.
•Internal sphincter (smooth muscle fibers).
3. Genital organs.
The pelvic parasympathetic system is concerned with emptying
of the urinary bladder and rectum.
The Parasympathetic Ganglia in the Head and Neck
There are four parasympathetic ganglia in the
head and neck:
1. Ciliary ganglion.
2. Submandibular ganglion.
3. Sphenopalatine (pterygopalatine) ganglion.
4. Otic ganglion.
Ciliary Ganglion
Type: it is a small parasympathetic ganglion (1-2 mm in
diameter).
Site: in the posterior part of the orbit.
Roots Entering the Ciliary Ganglion:
1. Sensory root: branch from nasociliary nerve.
2. Sympathetic root: from the internal carotid
sympathetic plexus.
3. Parasympathetic root: from nerve to inferior
oblique muscle (branch of oculomotor nerve).
Branches of the Ciliary Ganglion
The ciliary ganglion has 8-10 short ciliary nerves which
pierce the sclera around optic nerve.
They contain:
1. Sympathetic fibers: to the blood vessels of the eye.
2. Sensory fibers: to the cornea and iris.
3. Parasympathetic fibers: to the supply the sphincter
pupillae (for light reflex) and ciliary muscle (for
accommodation).
Submandibular Ganglion
Type: it is a small parasympathetic ganglion (2-3 mm in
diameter).
Site: it lies in the submandibular region on the upper part
of hyoglossus muscle.
Relations:
1. Superiorly: lingual nerve.
2. Inferiorly: deep part of submandibular gland and
its duct.
3. Medially: hyoglossus muscle.
4. Laterally: mylohyoid muscle.
Roots Entering the Submandibular Ganglion
1. Parasympathetic root: arising from the chorda
tympani nerve. It joins the lingual nerve then the
parasympathetic fibers leave lingual nerve to relay
in the ganglion.
2. Sympathetic root: arising from the plexus around
facial artery.
3. Sensory root: from lingual nerve (branch of
mandibular nerve).
Branches of the Submandibular Ganglion
1. Several small branches (mixed: parasympathetic
+ sympathetic + sensory fibers) pass directly from
the ganglion to supply the submandibular salivary
gland.
2. Similar branches join the lingual nerve to reach
the sublingual salivary gland.
Sphenopalatine (Pterygopalatine) Ganglion
Type: it is the largest parasympathetic ganglion (4-5 mm in
diameter).
Site: it lies in the pterygopalatine fossa.
Roots Entering the Sphenopalatine Ganglion:
1. Sensory root: two sensory branches arising from the
maxillary nerve.
2. Sympathetic root: the deep petrosal nerve from
sympathetic plexus around the internal carotid artery.
3. Parasympathetic root: the greater petrosal nerve
from facial nerve.
Branches of the Sphenopalatine Ganglion
1. Orbital branches: enter the orbit through the inferior orbital
fissure. They supply the orbital periosteum and the mucous
membrane of the sphenoid air sinus. Another fibers pass with the
zygomaticotemporal nerve to the orbit, where they branch off to
join the lacrimal nerve to supplies lacrimal gland.
2. Pharyngeal branch: to supply the mucous membrane of the
nasopharynx.
3. Greater palatine nerve: to supply the mucous membrane of the
hard palate and part of the nose.
4. Lesser palatine nerve: to supply the mucous membrane of the
soft palate and the palatine tonsil.
5. Short sphenopalatine nerve: to supply the mucous membrane of
the upper part of the lateral wall of the nose and nasal septum.
6. Long sphenopalatine nerve: to supply the mucous membrane of
the anterior part of the hard palate.
Otic Ganglion
Type: it is a small parasympathetic ganglion.
Site: in the infratemporal fossa just below foramen ovale.
Roots Entering the Otic Ganglion:
1. Motor root: arising from nerve to medial pterygoid
muscle.
2. Parasympathetic root: formed by lesser superfacial
petrosal nerve which carries preganglionic
parasympathetic fibers from tympanic branch of
glossopharyngeal nerve.
3. Sympathetic root: from the plexus around middle
meningeal artery.
Branches of the Otic Ganglion
1. Motor branch: to tensor palati muscle and another
branch to tensor tympani muscle.
2. A communicating branch: to auriculotemporal nerve,
this branch is formed of:
a. Sympathetic fibers: to supply the blood vessels
of parotid gland.
b. Parasympathetic fibers: secretomotor to parotid
gland.
The Parasympathetic Ganglia in the Head and Neck
Ganglion
Nucleus Parasympathetic Sensory
Sympathetic
root
root
root
EdingerNasociliary
Ciliary
Westphal Oculomotor nerve Nasociliary nerve from
internal carotid
plexus
Greater
Deep petrosal
Sphenopalatine Superior superfacial
Maxillary nerve from
salivary petrosal nerve
internal carotid
from VII nerve
plexus
Chorda tympani
Plexus around
Submandibular Superior nerve from VII
Lingual
facial artery
salivary nerve
Lesser superfacial
Plexus around
Otic
Inferior petrosal nerve
Mandibular middle
salivary from IX nerve
“Motor “ meningeal
artery
Dorsal
Vagus nerve
Many plexus
Many ganglion motor
Many
nerves
in the different nucleus
of vagus
organs
Organs
supplied
Sphincter
pupillae and
ciliary muscles
Lacrimal glands;
glands of nose,
palate, mouth
and pharynx
Submandibular
and sublingual
glands
Parotid gland
Heart,
Respiratory
system, Abd.
viscera
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